Apparatus for aligning preengraved projectiles in rifled firearms



Dec. 14, 1948. c. w. MUSSER 2,456,011

APPARATUS FOR ALIGNING' PREENGRAVED PROJECTILES IN HIFLED FIREARMS Filed July 17, 1945 5 Sheets-Sheet l CLARENCE W- MLISSER imam,

Dec. 14, 1948. c. w. MUSSE 2,456,011

APP TUS FOR ALIGNING P ENGRAVED I ECTILES IN RIFLED FIREARMS Filed July 17, 1945 s Sheets-Sheet 2 CLARENCE W- MU55ER C. W. MUSSER APPARATUS ROJECTI Dec. 14, 1948.

FOR ALIGNING PREENGRAVED LES IN RIFLED FIREARMS Filed July 17, 1945 5 Sheets-Sheet 25 CLARENCE W- MUSSER yn/Mm C. W. MUSSER ARATUS FOR ALIGNING ROJECTILES IN RI 2,456,011 PREENGRAVED FLED FIREARMS Dec. 14, 1948.

5 Sheets-Sheet 4 Filed July 17, 1945 ELARENEEW- MUSJSER Dec. 14, 1948. c. w. MussER 2,456,011

APPARATUS GNING PREEN VED PROJECT]: RIFLED FIRE 5 Filed July 17, 1945 s Sheets-Sheet 5 ELAREN cc W- Musssa 3% ywzmzwm Patented Dec. 1'}, 1948 i. w i

APPARATUS FOR ALIGNING PREENGRAVED PROJECTILES IN RIFLE!) FIREARMS (Ilarence Walton Musser, Philadelphia, Pa.

Application July 17, 1945, Serial No. 605,614 i'llalms. (Cl. 89-1.?)

(Granted under the act oi March 3, 1883, as amended Aprll 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

My invention relates to the insertion of preengraved projectiles into rifled gun barrels and it has special reference to means operative during such insertion for bringingthe projectile engravings into correct register with the lands and grooves of the barrel's rifiing.

Broadly stated, the object of my invention is to simplify the insertion of pre-engraved projectiles into the rifled barrels of both breech loading and muzzle loading firearms.

A more specific object is to diminish the effort and time required to effect such insertion.

A further object is to make pre-engraved projectiles more readily useable in rifled weapons of the automatic reloading type.

A further object is to impart to pre-engraved projectiles the capability of engaging a gun's rifiing in instantaneous alignment and without necessitating special rotative manipulation.

A still further object is to provide a unique method and novel apparatus for accomplishing the foregoing.

In practicing my invention I attain the stated and other objects by supplementing pre-engraved projectiles of conventional construction with nov- 91 indexing detents which engage the barrels spiral rifiing grooves and thereby lead the projectiles preengraved teeth into those grooves in the automatic and uniquely effective manner presently to be described. Preferred forms and illustrative applications of such detents are shown by the accompanying drawings wherein:

Fig. 1 represents indexer detents of a button type applied in accordance with my invention to a pre-engraved projectile which is designed for use with breech loading firearms and which is shown about to be inserted into the rifled barrel of a breech loading gun;

Fig. 2 is a showing (somewhat enlarged) of the indexing buttons of Fig. 1 partially compressed into the projectile wall by contact with a chamfered rim which leads into the rifled barrel;

Fig. 3 similarly represents the Fig. 1 in-' dexing buttons entirely compressed into the projectile wall due to. contact with opposing rifiing lands as occasioned by projectile advancement into the barrel;

Fig. 4 reproduces area A of Fig. 2 in section and to enlarged scale and shows the constructional details of one of the indexing buttons when same is partially compressed into the projectile;

Fig. 5 similarly reproduces area B of Fig. 3 and shows details of the indexing button when some is fully compressed into the projectile;

Fig. 6 shows the indexing buttons of the earlier figures re-extended into register with spiral rifiing grooves as occasioned by still further projectile advancement into the barrel;

Fig. 7 reproduces area C of Fig. 6, in section and to enlarged scale and shows details of one of the indexing buttons when same is fully reextended into the rifling groove;

Fig. 8 is a section on line 8-8 through the two groove-registered indexer buttons of Fig. 6 enlarged and completed to represent the entire barrel circumference;

Fig. 9 illustrates the accompanying registration of, the projectiles rotating band with the barrel rifiing which the indexing buttons automatically effect upon full forward thrust of the projectile into the ammunitions firing position;

Fig. 10 is a section on line Ill-40 through the so indexed rotating band of Fig. 9 enlarged and completed to represent the entire barrel circumference;

Fig. 11 is an enlarged view from line |l-l| of Fig. 9 with such different portion of the barrel removed as to show one of the projectiles forward indexer buttons and the pre-engraved projectiles rear tooth that is aligned therewith along the path of a registering rifiing groove (shown by broken lines);

Fig. 12 shows button type indexer detents of the earlier figuresapplied in accordance with my invention to a pre-engraved projectile which is designed for use with muzzle loading weapons such as mortars and which is shown about to be inserted into the muzzle end of a rifled mortar barrel;

Fig. 13 represents indexer detents of a leaf spring design which are applicable to projectiles of either the breech loading or the muzzle loading type but which are shown as installed on a breech loading projectile such as Figs. 1 to 11 illustrate;

Fig. 14 is an enlarged longitudinal section from line i4i4 of Fig. 13 showing how each leaf spring detent resiliently protrudes from the projectile wall;

Fig. 15 is an enlarged section from line l5|5 of Fig. 13 showing one manner of securing each detent spring into its mounting slot;

Fig. 16a is a similar section from Fig. 13s line lG-IB supplemented by part of a rifiled barrel and showing compression of the indexer detent spring into its mounting slot due to contact with a rifling land; 4

Fig. 16b modifies Fig. 16a to show re-extension of the leaf spring detent into registry with a barrel rifiing' groove;

Fig, 17 represents indexer detents of a "resilient ear" design which are applicable to projectiles of either the breech loading or the muzzle loading type but which are shown as installed on a breech loading projectile of detachable-nose construction; and

Fig. 18 is a frontal view from line lit-I8 of Fig. 17 with the projectile nose piece removed to show further details of the resilient metal ring from whose periphery the ear detents extend.

Firearms and ammunition with which improvement is useable Pre-engraved projectiles for rifled weapons of a wide variety of types and calibers may be benefited by my improved self-indexing mechanism. The projectile and breech loading firearm of Figs. 1 to 11 are illustrative of these. The firearm there represented is a 75 mm. recollless weapon duplicating that shown and described by Kroeger- Musser patent application Ser. 577,830 filed February 14, 1945 for Recoilless firearm and ammunition therefor.

The barrel 32 thereof has an inside diameter of approximately 3 inches, and is rifled to secure the usual gains in accuracy and range which a spinning of the projectile in flight makes possible. The rifling represented has a right hand twist of one turn in 22 calibers (or approximately 65 inches of barrel 32) and utilizes the twenty-eight lands 33 with intervening grooves 34 which the drawings hereof show.

As the description proceeds it will become apparent that my improvements also are useable with pre-engraved projectiles designed for firing from muzzle loading as well as breech loading firearms, or for barrels either larger or smaller than 75 mm., or for barrels that utilize steepnesses of rifling twist other than one turn in 22 calibers, or that have twists in the left hand direction instead of the right, or that utilize either more or less than 28 lands with 28 intervening grooves. Such rifled barrels may, moreover, form a part of firearms of any conventional or special type and hence need not be restricted to the recollless type here shown as including a tapered open-breech chamber 46.

The accompanying ammunition round here illustratively shown is designed for use with the 75 mm. recollless firearm just described. It comprises a pre-engraved projectile 20 insertable into rifled barrel 32 plus a cartridge case 26 perforated in the manner and for the purpose stated by Kroeger-Musser application Ser. 577,830 and by an earlier Kroeger-Musser application Serial No. 536,590, now abandoned, filed May 20, 1944, for

'Recoilless firearms, ammunition therefore and ballistic design thereof. This complete round has an overall length of about 28 inches (of which approximately 13 inches are in the projectile 20) and a total weight of about 22 pounds (of which approximately 15 pounds are in the projectile).

The represented projectile 20 makes use of a rotating band 30 pre-engraved to assure more ready passage of the projectile through barrel 32's rifled bore. This band may be conventional in all respects; it is shown as being located close to the projectile bodys rear; and it has cut therein twenty-eight grooves 24 spaced to accommodate the twenty-eight lands 33 of barrel 32, as shown by Fig. 10. The intervening band teeth 25 similarly mate with the twenty-eight barrel grooves 34 when the projectile has been fully loaded into the barrel.

This illustrative projectile 20 further makes use of a bourrelet 2| encircling the projectile body relatively close t the bodys forward nose. This bourrelet is spaced from the rear rotating band by a center-line to centerline distance of the order of four and one-half inches. For the illustrative barrel rifling twist of one turn in 22 callbers (or about 65 inches of barrel 32) such an axial spacing corresponds to about of a rifling rotation. This means that an axial advance of four and one-half inches through barrel 32 will cross two of the spiral lands 33 and two of the spiral grooves 34.

As the description proceeds it will become apparent that my self-indexing improvements also are useable with pre-engraved projectiles for firearms of the muzzle loading as well as the breech loading type, or forming parts of ammunition other than perforated case-type shown, or having calibers either larger or smaller than mm., or that carry the pre-engravings directly on the projectile body (rear portion for breech loading and forward portion for muzzle loading) instead of on a separate rotating band, or that have bourrelet-to-rotating band spacings either greater or less than four and one-half inches, or that have no well defined bourrelets, or that are designed for use in barrels rifled with either more The problem to be solved As co-pending Kroeger-Musser application Serial No. 536,590 more fully brings out, pre-engraving of projectiles tends to increase the overall eflioiency of the weapons in which they are used. Important advantages include a lowering of the force needed to advance the projectile through the barrel plus elimination of engraving pressures behind the projectile and of attendant swedging" erosion of the bores lands. In the case of illustratively shown recollless type weapons, which are fast becoming highly important for military use, projectile rare-engraving is especially valuable as it makes complete recoil neutralization relatively more easy and reliable.

Heretofore, however, these obvious advantages of pre-engraved projectiles have been attended by substantial extra time and efiort required to load same into rifled barrels. In military gunnery, particularly, loading time and effort are of paramount importance and must be minimized before full benefit of the pre-engraving virtues can be realized.

Specifically, the handicap heretofore suffered by Dre-engraved projectiles has been the necessity for matching the projectiles engraved teeth and grooves with the complementary grooves and lands of the barrels rifling. The process of effecting this registration is time consuming and in the heat of battle may be most troublesome. Moreover, this registration requirement has thus far precluded widespread use of pre-engraved projectiles in weapons of the automatic reloading ype.

What is needed, therefore, and what my here disclosed invention has supplied, are indexing facilities which are self-aligning and automatic,

and which may always be relied upon to lead the engraved portion of the projectile into accurate registry with the barrels riflings.

Button type detents applied to breech loading projectiles In the illustrative construction for breech loading use which Figs. 1 through 11 show, my new projectile aligning mechanism takes the form of two indexing buttons 2828' projected from the bourrelet 2| at a rotative separation ot 180 and at a forward axial spacing from rotating band 30 of about four and one-half inches. These buttons may satisfactorily be made of a relatively soft metal," such as brass, and each may satisfactorily be mounted upon a washer 29 of compressible rubber or other material that imparts radial resilience to the button support. One highly practical form of such mounting is illustrated by Figs. 4-5, 7-8.

As will be more fully brought out presently, these two simple and inexpensive rotative positioning buttons 28-28 are capable of automatically indexing the engravings on projectile 20's rotating band 30 into accurate registry with the rifling of barrel 32 instantaneously upon forward {thrust of the projectile into the barrel and without necessitating special--rotative manipulation. Since the illustrative complete 75 mm. ammunition round thus rotatively positioned weighs over 20 pounds, an exceedingly high degree of fi'ectiveness is achieved.

Operation of self-aligning indexing detents Loading pro-engraved projectiles bearing my herein described indexing detent improvement is a relatively simple and automatic process. To effect" this loading, a gunner merely thrusts the complete round into the gun chamber 46 (see Fig. 1), and then forwardly rams the projectile home in the gun barrel 32 (see Fig. 9) by exerting simple axial pressure on the head of the rounds cartridge case 25.

In the course of thus inserting the projectile in the barrel, the indexing detents 28--28' contact the 'chamfered rim portion 41 of barrel 32 (see Figs. 1 to 5, 6 and 9) and are thereby partially compressed inwardly as shown in Fig. 4. Should the detents immediately index riiiing grooves 33 upon entering the barrel 32, return to their previous extended position immediately occurs, concomitantly resulting in button-to-groove registration, as shown in Figs. 6-7-8.

Should, however, the detents 2828 first meet spiral lands 33 upon entering barrel 32, total inward compression of the detents occurs, as shown by Figs. 3 and 5, as they ride on the respective lands so contacted. This state continues until the forward movement of the projectile brings the detents 28-28' opposite corresponding spiral grooves 34. Immediately, then, the detents are forced to re-extend outwardly under pressure exerted by the resilient washers 29-49, resulting in detent-to-groove registration at that particular point in the barrel 32, as represented by Figs. 6-7-8.

Upon such registration of detents 28-28 with riiling grooves 34, forward progress of the projectile in barrel 32 will be a spiral motion. The attendant projectile rotation is efiected by the action of the detents 28-48 following in the tracks of spiral grooves 34, as indicated byFig. 11. These detents are spirally aligned with rotating-band teeth as later described.

rotating band 30 will be properly positioned so that its teeth 25 and grooves 24 accurately align with the riding grooves 3| and lands 33, respectively. Registry of the pre-engraved band 30 with the riflings of barrel 32 takes place immediately thereafter, as represented by Figs. 9-10. The thus-loaded projectile 20 is then ready for firing.

The just explained automatic operation of my detent indexer facilities thus effects the desired matching of projectile engravings 2425 with the barrel riflings 33-34 without the special manipulations and time consuming efforts which heretofore have been I an accepted "necessary ev in the use of pre-engraved projectiles.

Construction and installation of .button type indexing detents In my well tested and successful product of Figs. 1 to 11 that is adapted for 75 mm. use, I have mounted each indexer button 2828 in a projectile side wall hole of the type which Figs. 4-5, 7-8 illustrate at ll-4l'. In the 75 mm. projectile represented, each of these holes ll-ll' is approximately one quarter inch in diameter, has a depth of the general order shown, and its base is cone shaped (included angle of about 140) for a purpose later to be made evident.

Within each hole ll-H' I place a ring shaped Washer 2929'. of resilient material (such as of neoprene" rubber) in contact with the coneshaped base thereof, as shown by Figs. 7-8 (also Figs. 4-5). For the 75 mm. projectile represented, each of these washers has an outside diameter of slightly less than one-quarter inch, an inside diameter of about one-eighth inch, and a thickness of less than one-eighth inch.

The index button 28 or 20 is next inserted into hole II or I to rest upon the resilient washer 29 or 29. Each of these buttons is preferably made of a relatively soft metal such as brass and has the shape illustratively shown in Figs. 4-5, 7-8, 11 as including an outer narrow portion integrally joined with an expanded inner portion. The protruding stud-like outer portion has a diameter of approximately 0.181 inch and a length of about 0.058 inch. The first of these dimensions is slightly less than the width of rifling grooves 33 into which the button is at times protruded, as shown by Figs. 6-7-8.

Each index buttons expanded inner portion is at all times positioned within hole ii in the projectiles wall, as shown by Figs. 4-5, 7-8. This expanded inner button part has an outside diameter slidably mating with the inner wall of the quarter-inch hole ll, is of sufficient length to resist sidewise or tipping movement with respect to the hole, and has a base that is cone-shaped (included angle of about concavely as shown by Figs. 4-5, 7.

When the index button 28 is placed in hole 4| upon resilient washer 29 (much as in Fig. 7), the juncture of the outer narrow and inner expanded portions is about flush with the projectiles outside wall surface. By means of a circular punch (not shown), having a concavity which fits over the buttons projecting end, the projectile metal which rims hole ll at this surface is crimped in about the expanded inner lip of button 28 as indicated at 42 in Figs. 4-5, 7-8, 9, 11. This circular crimp 42 thereafter prevents button 28 from fallin out of hole 4|, and leaves only the narrower portion of the button projecting from the projectile wall.

This outward projection on the part of each 7 button 28-28 results from a continuous expansive urge by the resilient washer 28 or 29 tha is compressed beneath the button base. At

rent times this washer compression has the va ing degrees respectively indicated by Figs. 7/ 4 and 5. Button 28 freely slides in projectile wall hole 4| and thereby quickly expands in going from the Fig. 5 condition to the Fig. 7 condition.

The dimensions stated for the indexing buttons 28-28, washer 29-29 and holes 4l-4i' in which these parts are placed will of course vary with different caliber guns and the measurements of a particular weapons riflings. The narrowmost projecting portion of these buttons will, however, always be of a diameter which can enable the buttons readily to fall into and traverse the grooves 34 of the rifling for which the projectile is intended.

Positioning and number of indexing detents As already indicated, the two represented indexer detents 28-28 are illustratively shown as projecting radially from the bourrelet 2| which is the forwardmost untapered portion of the projectile body 20. When so installed on the projectile for resilient compression thereinto, these unique index detents function correctly to register the projectiles pre-engraved portion 24-25 with barrel 32's riflings 33-34 when the projectile is thrust into its proper firing position inwhich may be used. For the illustrative '75 mm.

projectile shown this number may vary from one to twenty eight. Tests show that one is sufficient; however, for purposes of added reliability the illustrated two are preferable. Even larger caliber projectiles, such as 105 mm., have likewise been indexed correctly and reliably by a single pair of detents.

Spacing of indexing detents from projectile preengravings As previously indicated, the axial spacing between the forward indexing detents 28 and the rear pre-engravings 24-25 may be either greater or less than the four and one-half inch separation illustratively described for the represented '75 mm. projectile 20. While there is no limitation to the maximum amount of such axial spacing, it will be seen that there is a minimum separation distance below which my indexing detents may not always operate in their intended manner. This minimum distance between rear engravings 24-25 and forward indexing detents 28 must in all cases be sufiicient to assure that the detents will register with spiral rifiing grooves 34 and thereby index those engravings for similar registration before same have been forwardly advanced to rifled barrel 32's rear or loading end.

It will be apparent that the most dimcult indexing situation arises when the index detents 28 Thus, the presence of a chance to first contact the raised surfaces of lands 38 upon initially entering the rear or loading end of the rifled barrel 32. Under this condition the projectile will be required totravel forward its greatest lengthwise distance before the axially advancing buttons move away from the spiral lands 33 initially contacted and expand into registration with adjoining spiral barrel grooves 34. In such a case, the necessary axial spacing between the engravings 24-25 and the detents 28-28 must be no less than the axial distance required for the rifiing helix pattern to be repeated in the same plane.

This requirement may be further clarified by citing the illustrative 75 mm. recoilless rifle and the represented projectile 28 as an example. This weapon's barrel 32 utilizes 28 lands and 28 grooves rifled with a twist of one turn in 22 calibers or 65 inches of the barrel length. For the projectile indexing detents 28 to register with the first spiral groove 34 encountered in the above-mentioned "most diflicult indexing situation," the leading edge of each detent must pass completely over one spiral land 33 and into the adjoining spiral groove 34. The necessary axial distance required to be traversed by the detent can be shown to be equal to 65 inches multiplied by the fraction of %6 s) or approximately two and one-third inches.

From this example it will be evident that the greater the number of lands and grooves in a barrel that is rifled with a given twist, the less will be the axial spacing required between the projectiles rear pre-engravings 24-25 and the forward index buttons 28, and vice versa. Similarly, in a barrel having a given number of lands and grooves, the stated minimum spacing will diminish as the steepness of twist is increased, and vice versa. Thus, the named minimum spacing requirement will vary according to both of the stated factors. Both of those factors must therefore be considered in selecting the placement positions for the index detents upon a preengraved projectile which is to be used in a particular rified barrel.

Establishing rotative location of indexing detents To properly locate the index detents 28 on the projectile as required, in accordance with the foregoing and other considerations, for correct projectile engravings-to-riflings registry, I have developed an exceedingly simple but highly effective apparatus. This apparatus (not shown) consists of a hollow metal cylindrical fixture having one end closed off and having a length roughly equivalent to that of the projectlles untapered portion.

The bore of this cylinder simulates that of the rifie in which the projectile is to be used, having the same internal diameter and rifling grooves 34 and lands 33. In fact, a complete cylindrical section of an actual rifle barrel may be used for this purpose. In one satisfactory arrangement, this fixture is horizontally mounted so as to be rotatable in a supporting stand which is capable of being clamped to the work table of a drill press.

The projectile is fitted into this cylindrical fixture, base or rear end first to rest against the cylinder's closed end. In so doing, the projectiles pre-engraved portion 24-25 is placed in respective interlocking alignment with the cylinders riflings. Thus, this pre-engraved portion being the form of a helix which matches the spiralled rifiings, its grooves 24 will mate with rifiing lands 38; and its teeth 25 will engage rifiing grooves 34.

Were these pre-engraved, helically cut grooves cated by' Fig. 11, this interlocking alignment would likewise be continued. While no such ex-' tensions are used or even required, it will be apparent that my indexing detents 28 must be located on the projectile wall at some point on the heliral paths which would be taken by such extensions of the pre-engraved teeth 25 in order to accomplish reg strationwith rifiing grooves 34.

Preferably, too, the indexing detents 28 should be placed substantially ahead of the .projectiles pre-engraved portion, such as on the bourrelet 2!, in order that the engravings can be properly indexed with the spiral riflings before the engraved portion 38 actually enters the barrel 82. For this purpose the four and one-half inchspacing illustratively named has been shown to be more than ample (a minimum of two and onethird inches would suffice) for projectiles designed to be used with the '75 mm. barrel represented at 82. I

When the projectile is established in the cylindrical fixture as earlier described, the supporting stand is bolted to the drill press table'in a position which permits a drill to penetrate a guide hole that extends through the cylinder wall. This guide hole is'situated so as to exactly intersect the center-line of a helical rifiing groove 84 immediately therebeneath (see Fig. 11).

Through this guide hole the drill is directed to form the hole 4| (see Figs. 4-5, 7-8, 9, 11) in which the index button 28 is to be placed. Since the guide hole cuts through the center-line of a barrel rifling groove 34, the resultant hole 4| drilled in the projectiles wall will intersect the center-line of the helical path representing an extension of the engraved tooth 25-which mates with that rifling groove (as was previously outlined). It follows, therefore, that the index button 28-later positioned in this hole 4! will likewise mate or register with that and all the other equivalent dimensioned rifiing grooves 34,

The number of indexing buttons to be used is optional, as previously indicated. Although a minimum of two is preferable, more or less may be employed as desired, limited only by economy and the number of rifiing grooves 34 with which they are to register. For drilling the number of holes desired, the earlier described rotatable fixture is equipped with a convenient braking device which enables the fixture to be kept stationary during the drilling operation. In addition, each guide-hole 'on the cylindrical fixture is indexed so that its exact position may be duplicated without error.

Use of indexer on muzzle loading projectiles Although the automatic indexer facilities of my invention will find many applications with breech-loading weapons and ammunition such as Figs, 1 through ll'typify, use of these facilities is not limited thereto. By simply interchanging the indexer and pre-engraving locations on the projectile, same may be adapted for use in muzzle loading guns.

Reference to Fig. 12 will show my indexer improvement thus applied to a pre-engraved projectile used in a mortar, a muzzle loading weapon. the only modification over breech loading projectiles required is there shown to be a reversal of the relative positions of the indexer detents 28a and the pre-engraved portion 24'25' on the projectile i. Thus, as depicted, the indexer detents (only one shown) are nearer the prolectiles base than the engraved portion which is closer to the fuzed nose 52.

when the gunner drops Fig. 12's mortar projectile 5| into the muzzle end of rifled mortar barrel 53, base end first, therear positioned selfaligning indexer detent 28a registers with a rifiing groove (not shown) in that barrel. Automatic alignment of the forward pre-engraved projectile portion 24'25 then follows in exactly the manner earlier described and shown (Figs. 1 to 11) in the case of breech loading firearms and ammunition therefor.

Alternative construction for indexer detents As earlier intimated, a number of alternative indexer detent constructions are possible in addition to the "button type which Figs. 1 to 12 hereof show. Two of these, respectively referred to as "leaf spring and resilient car, will now be described.

The leaf spring form of detent is shown by Figs. 13-14-15-16 to comprise a leaf spring 28b secured at one of its ends in a recess 51 by a crimp or spot weld as shown at 58. This spring projects from recess 51 which together with the spring coincides with a spiral extension of an engraved projectile tooth 25. This spiral also matches the helical gun barrel riflings (one groove of which is represented by the dotted lines in Fig. 13).

From the earlier given explanation of my indexer buttons operation, the automatic registry made possible by this spring indexing device will be obvious. Spring 28b compresses as does button 28 upon striking a land 33, (see Fig, 16a) and later re-extends to engage a rifling groove 34 (see Fig. 161)). Function and resultthus are the same as for the button indexer detents 28 of Figs. 1 to 12.

The resilient ear" form of alternative indexer detent construction is shown in Figs. 17-18 at 28c28'c. This modification is particularly useful in projectiles (smaller sizes andothers) where the removable nose portion joins the projectile body at a diameter only slightly less than the body's maximum. It consists of a washer 6i of resilient material, such as spring steel or phosphor-bronze, fastened into the Fig. 17 position by simply screwing into place the fuzed nose 86. This washer M is ring-shaped, having a hollow central opening equivalent in size to the diameter of the projectiles mouth 61 into which the fuzed nose 88 is screwed. One or more indexing "ears" 28c-28'c protrude radially from this washer 6! as shown by Figs. 17-18. Once the proper rotative positioning of these indexer ears 280 is determined (for correct engravings-to-rifiing registry), the washer can there be rotatively fixed by conventional keying means. One such keying arrangement uses a dowel pin (not shown) in the end face of projectile mouth 67 to receive a matching hole in washer (ii. In another keying method that is shown by Figs. 17-18, the washer 8| has therein a depression 69 which mates with a hole H in the projectile mouths end face.

The operation of this "resilient ear indexer is also based on the earlier described method underlying use of my "button type indexer facilities (Figs. 1 to 12). The springy projections 280-280 collapse into the tapered margin 12 of the projectile's forward body portion upon striking a rifling land (not shown). Re-extension to enter a rifling groove next occurs upon continued l 1 forward axial movement of the projectile in the gun barrel. The tapered margin 12 permits this compression of indexing projections 2,8c-28'c below the circumference of the projectile, thereby avoiding jamming of the indexer ears against the barrels lands.

Summary Still other constructions for the projectile's indexer detents 28 are of course possible. Basic requirements to be met are that each installed detent member be aligned spirally with one of the projectile's pre-engraved teeth; that it be sufficiently spaced axially from the pre-engravings to assure registry with a rifling groove before the pre-engravings have been advanced to the barrels loading end; and that it have such radial resilience as to yield inwardly when a rifling land is first encountered and then spring outwardly again when registry with a rifling groove has been established.

Any form of construction which satisfies the foregoing may be applied either to breech loading projectiles where the indexer detents are positioned ahead of the pre-engravings or to muzzle loading projectiles where the indexer detents are positioned behind the pre-engravings.

In fact, pre-engraved objects other than projectiles may have their entrance into spirally grooved bores other than firearms barrels facilitated by the indexer detent facilities which have been invented by me as described herein. In all such applications (firearms ammunition and other) the process of self-alignment will be entirely automatic and completely independent of former requirements for rotative manipulation.

Speaking of firearms uses only, it will be evident that my herein disclosed improvements have extended the utility and simplified the use of pre-engraved projectiles in rifled weapons of all types; have simplified the insertion of pre-engraved projectiles into the rifled barrels of both breech loading and muzzle loading firearms; have diminished the effort and time required to effect such insertion; have made pre-engraved projectiles more readily useable in rifled weapons of the automatic reloading type; and have imparted to pre-engraved projectiles the capability of engaging a gun's rifling in instantaneous alignment and without necessitating special rotative manipulation.

With possibly minor changes that will not depart from the spirit and intent of my invention,

the new self-indexing facilities here described may be applied to any pre-engraved projectile or the like that is intended for use in a rifle gun barrel or other equivalent tube. My inventive improvements are therefore extensive in their adaption and are not to be restricted to the specific form here disclosed by way of illustration.

I claim:

1. In combination, a tubular bore interiorly rifled with spiral lands and grooves, a cylindical member for passage through said bore having pre-engraved grooves and teeth registerable with their complementary counterparts in the bores rifling and exteriorly encircling said member towards the end thereof that is last to enter said bore when the member is axially inserted thereinto, and an indexing detent resiliently protruded radially from said cylindrical member astride a continuation of the helicalline of one of the members said pre-engraved teeth and so spaced axially from that tooth as to precede same into said bore upon said axial insertion of the cylindrical member into the bore whereby then to engage with one of said bores spiral rifling grooves and by following in that groove so to rotate the cylindrical member during further axial advancement thereof into the bore as automatically to bring that member's said pre-engraved grooves and teeth into accurate registry with said bores rifled lands and grooves.

2. In combination, a gun barrel interiorly rifled with spiral lands and grooves, a projectile for firing from said barrel having pre-engraved grooves and teeth registerable with their complementary counterparts in the barrels rifling and encircling said projectile towards the end thereof that is last to enter said barrel during loading, and an indexing detent mounted on said projectile astride a continuation of the helical line of one of the projectiles pre-engraved teeth and in such axially spaced relationship to that tooth as to precede same into the barrel during loading, said indexing detent being there resiliently protruded radially from the projectile for engagement with one of said barrels spiral grooves upon axial thrusting of the projectile into said barrel whereby the resultant following of said detent in said groove then so rotates the projectile as automatically to bring the pro-' jectiles said pre-engraved grooves and teeth into accurate registry with said barrels rifled lands and grooves.

3. In combination, a gun barrel interiorly rifled with spiral lands and grooves, a projectile for firing from said barrel having pre-engraved grooves and teeth registerable with their complementary counterparts in the barrels rifling and encircling said projectile towards the end thereof that is last to enter said barrel during loading, and an automatic indexing detent radially protruded from said projectile astride a continuation of the helical line of one of the projectile's said pre-engraved teeth and in such axially spaced relationship to the tooth as to precede same into the barrel during loading, said detent being there resiliently mounted to permit inward radial compression when said projectile is first axially thrust into said barrel but outwardly expanding into a spiral barrel groove upon initial registry therewith and thereafter following said groove during further axial advancement of the projectile into the barrel whereby then so to rotate the projectile as automatically to bring the projectile's said pre-engraved grooves and teeth into accurate registry with said barrels rifled lands and-grooves.

4. In combination, a gun barrel interiorly rifled with spiral lands and grooves, a projectile for firing from said barrel having pre-engraved grooves and teeth registerable with their complementary counterparts in the barrels rifling and encircling said projectile toward the end thereof that is last to enter said barrel during loading, and an automatic indexing detent radially protruded from said projectile astride a continuation of the helical line of one of the projectile's said pre-engraved teeth and in such axially spaced relationship to that tooth as to precede same into the barrel during loading, said detent being there resiliently mounted to permit inward radial compression when said projectile is first axially thrust into said barrel and remaining so compressed upon passage over one of the barrels said spiral lands but outwardly expanding into an adjacent spiral barrel groove upon initial registry during further axial advancement of the projectile in the barrel whereby then so to rotate the projectile as automatically to bring the projectiles said pre-engraved grooves and teeth into accurate registry with said barrels rifled land and grooves.

5. In combination, a breech-loading gun barrel interiorly rifled with spiral lands and grooves, a projectile for firing from said barrel having preengraved grooves and teeth encircling the rear portion thereof and registerable with their complementary counterparts in the barrels rifling, and an indexing detent mounted at the forward portion of said projectile astride a continuation of the helical line of one of the projectile's said preengraved teeth and there resiliently protruded radially from the projectile for engagement with one of said barrels spiral grooves upon forward axial thrusting of the projectile into the breech end of said barrel whereby the resultant following of said forward detent in said groove then so rotates the projectile as automatically to bring the projectiles said rearward pre-engraved grooves and teeth into accurate registry with said rifled lands and grooves at said barrels breech end.

6. In combination, a muzzle loading gun barrel interiorly rifled with spiral lands and grooves, a projectile for firing from said barrel having pre-engraved grooves and teeth encircling the forward portion thereof and registerable with their complementary counterparts in the barrels rifling, and an indexing detent mounted at the rear portion of said projectile astride a continuation of the helical line of one of the projectiles said pre-engraved teeth and there resiliently protruded radially from the projectile for engagement with one of said barrels spiral gropves upon rearward axial thrusting ofthe projectile into the muzzle end of said barrel whereby the resultant following of said detent in said groove then so rotates the projectile as automatically to bring the projectiles said forward pre-engraved grooves and teeth into accurate registry with said rifled lands and grooves at said barrels muzzle end.

7. In a projectile for firing from the rifled barrel of a breech loading gun, the combination of pre-engraved grooves and teeth encircling said projectile towards the rearward end thereof and registerable with spiral lands and grooves'in said upon forward axial thrusting of the projectile into said barrel and by following in said groove then so rotate the projectile as automatically to bring the rear pre-engravings thereon into acl curate registry with said'barrel's rifling.

8. In a projectile for firing from. the rifled barrel of a muzzle loading gun. the combination of pre-engraved grooves and teeth encircling said projectile towards the forward end thereof and registerable with spiral lands and grooves in said barrels rifling, and an indexing detent resiliently protruded radially from said projectile towards the rearward end thereof and astride a continuation of the helical line of one of the projectiles said forward pre-engraved teeth whereby to engage with one of said barrels spiral rifling grooves upon rearward thrusting of the projectile into the muzzle end of said barrel and by following in said groove then so rotate the projectile as automatically to bring the forward pre-engravings thereon into accurate registry with said barrel's rifling.

9. In combination, a rifled cylindrical member and a tube having a rifled bore adapted so as to enable the respective riflings to become registered one with the other when the cylindrical member is inserted into the tube, and resilient means separate and independent of the teeth and grooves of both the said rifled member and rifled tube adapted to cooperate therewith by yielding so as not to cause interference when said member is moved axially within and relative to said tube, but capable of functioning as an indexing device to cause meshing register between riflings of cylindrical member and the riflings of the tube when said member is axially inserted into the tube.

10. In a projectile for flring from the rifled barrel of a gun, the combination of pre-engraved grooves and teeth encircling said projectile towards the end thereof and registerable with the spiral lands and grooves in said barrels riflings, and an indexing detent mounted on said projectile astride a continuation of the helical line of one of theprojectile's pre-engraved teeth and in such axially spaced relationship to that tooth as to precede same into the barrel during loading,

said indexing detent being there resiliently protruded radially from the projectile for engagement with one of said barrels spiral grooves upon axial thrusting of the projectile into said barrel whereby the resultant following of said detent in said groove then so rotates the projectile as automatically to bring the projectile's said pre-engraved grooves and teeth into accurate registry with said barrels rifled lands and grooves.

CLARENCE WALTON MUSSER.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 45,898 Berdan Jan. 10, 1865 182,278 Hotchkiss Sept. 19, 1876 1,548,818 Bijur Aug. 11, 1925 1,602,037 Mixsell Oct. 5, 1926 v FOREIGN PATENTS Number Country I Date 4,926 Great Britain Mar. 29, 1890 306,405 Germany Feb. 20, 1920 

